Collapsible/expandable prosthetic heart valves with non-expanding stent posts and retrieval features

ABSTRACT

A frame structure for a collapsible and re-expandable prosthetic heart valve. The frame structure includes an annular annulus portion that is configured for implanting in or near a patient&#39;s native heart valve annulus. This annulus portion of the frame structure may include a plurality of annularly spaced commissure post structures interconnected by connecting structures. The commissure post structures may be more resistant to annular collapse than the connecting structures. In the case of a prosthetic aortic valve, the frame structure may also include an annular aortic portion. The aortic portion may include a plurality of attachment points (for tethers) closest to the annulus portion. Such attachment points and tethers can facilitate re-collapse of a partly deployed valve in the event of a need to reposition or remove the valve.

This application claims the benefit of U.S. provisional patentapplication No. 61/001,976, filed Nov. 5, 2007, which is herebyincorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

This invention relates to prosthetic heart valves of the kind that canbe collapsed to a reduced circumferential size for delivery to thevalve-implant site in a patient (e.g., in or through the lumen oftubular delivery apparatus such as a catheter, a trocar, laparoscopicapparatus, or the like). When the valve is at the implant site, it canbe released from the delivery apparatus, which allows the valve tore-expand (or to be re-expanded) to its larger, full, operational,circumferential size. This re-expansion may be wholly elastic, whollyplastic, or partly elastic and partly plastic. Elastic re-expansion maybe achieved by using a springy metal such as nitinol in the valve.Plastic expansion may be achieved, for example, by inflating a ballooninside the valve. In addition to restoring the valve to the size thatpermits it to operate as a valve (i.e., a size at which the flexibleleaflets in the valve can open and close), re-expansion of the valvecauses the valve to engage native tissue of the patient at the implantsite, thereby anchoring the valve at that location in the patient.

Terms like retrieval, repositioning, and removal refer to the ability toreturn the valve to the delivery apparatus after it has wholly or partlyleft that apparatus. Such retrieval may be done to allow the valve to bemoved to another, different location or orientation in the patient(so-called repositioning), or to completely remove the valve from thepatient (so-called removal). Returning the valve to the deliveryapparatus involves re-collapsing the valve to its reducedcircumferential size. If the valve is to be repositioned, then when thevalve is at the desired new location or orientation in the patient, thevalve leaves the delivery apparatus again, and it again expands (or isexpanded) to its full operating size.

There are many considerations involved in designing a prosthetic heartvalve that can collapse to a relatively small diameter without, forexample, damaging the flexible leaflets of the valve, and that can alsobe re-collapsed (e.g., for repositioning) after expansion or partialexpansion at the implant site in the patient. There is therefore anon-going need for improvements in these and other areas of prostheticheart valve design.

SUMMARY OF THE INVENTION

In accordance with certain possible aspects of the invention, a framestructure for a prosthetic heart valve may include a plurality ofY-shaped structures disposed in an annular array in which the Y-shapedstructures are spaced from one another in a direction that is annular ofthe array. For example, each of the Y-shaped structures may provide acommissure post region of the prosthetic valve. Each of the Y-shapedstructures may include a base member having a first free end portion(providing, for example, a commissure post tip of the prosthetic valve)and an opposite second end to which a first end of each of two arms ofthe Y-shaped structure are connected. The arms of each of the Y-shapedstructures diverage from one another in a direction away from the secondend of the associated base member to define an annular space between thearms. The frame structure may further include a plurality of connectingstructures, each of which extends between a respective pair of annularlyadjacent ones of the Y-shaped structures, and each of whichinterconnects the Y-shaped structures in the associated pair. Each ofthe connecting structures may be collapsible and re-expandable in theannular direction. Each of the Y-shaped structures is preferablysufficiently strong to maintain at least 75% of the space between itsarms when the array is subjected to an annular collapsing force thatcollapses it to 50% of an initial annular size.

In accordance with another possible aspect of the invention, each of theabove-mentioned connecting structures may be connected to the arms ofthe above-mentioned Y-shaped structures in the associated pairs but notto the base members of those Y-shaped structures.

In accordance with yet another possible aspect of the invention, each ofthe above-mentioned Y-shaped structures may further include a linkingmember that interconnects the arms of that Y-shaped structure at alocation that is spaced from the second end of the base member of thatY-shaped structure.

In accordance with still another possible aspect of the invention, theabove-mentioned array may lie in an approximately tubular geometricspace that surrounds a central longitudinal axis. The base member ofeach of the above-mentioned Y-shaped structures may be approximatelyparallel to this longitudinal axis. All of the above-mentioned firstfree end portions may point in a first direction along this longitudinalaxis. The first free end portions may all extend farther in the firstdirection than any portions of any of the above-mentioned connectingstructures.

In accordance with yet another possible aspect of the invention, noportions of any of the above-mentioned Y-shaped structures may extend asfar opposite the above-mentioned first direction as portions of theabove-mentioned connecting structures. Again, in such a case, each ofthe Y-shaped structures may further include a linking member thatinterconnects the arms of that Y-shaped structure at a location that isspaced from the second end of the base member of that Y-shapedstructure. Alternatively, when such linking members are provided, thelinking member of each of the Y-shaped structures may extendapproximately as far opposite the first direction as portions of theconnecting structures.

In accordance with still another possible aspect of the invention, theframe structure may further include an aortic portion that is spacedfrom the above-mentioned Y-shaped structures and connecting structuresin the first direction. The aortic portion may be annular about theabove-mentioned longitudinal axis and is annularly collapsible andre-expandable. The frame structure may further include a plurality ofstrut members for attaching the aortic portion to the Y-shaped andconnecting structures of the frame structure. In such a case, the aorticportion may include a plurality of closed-perimeter, open-centered cellsdisposed in an annular array in which connection points betweenannularly adjacent cells are at intermediate points along sides of thecells and each cell includes first and second ends that respectivelypoint in the above-mentioned first direction and opposite that firstdirection. Further in such a case, the second end of each of the cellsmay include an eyelet or other such feature for attaching a tethermember that can be used to pull that eyelet or other such featureradially in toward the above-mentioned central longitudinal axis.

In accordance with yet another possible aspect of the invention, a framestructure for a prosthetic heart valve may include an annulus portionthat is annular about a longitudinal axis and that is annularlycollapsible and re-expandable. The frame structure may further includean aortic portion that is also annular about the longitudinal axis andthat is also annularly collapsible and re-expandable. The framestructure may still further include a plurality of strut members forconnecting the annulus portion to the aortic portion at a plurality ofpoints that are spaced from one another in a direction that is annularof the aortic portion. The aortic portion may include, at each of theabove-mentioned points, a pair of arm members that begin at that pointand that diverge from one another in the first direction with anincluded angle between the arm members of less than 90°. Each such armmember extends in this fashion from its beginning point until itconnects to an annularly adjacent arm member that began from anotherannularly adjacent one of the above-mentioned beginning points. Theaortic portion preferably includes no other structure between annularlyadjacent ones of the arm members that thus connect to one another andthat start from different ones of the above-mentioned beginning orstarting points. Similar principles can be alternatively or additionallyapplied to the annulus portion of the frame structure.

In accordance with still another possible aspect of the invention, aframe structure as summarized in the preceding paragraph may furtherinclude a plurality of closed-perimeter, open-centered cells between thearm members that start from each of the above-mentioned starting points.These cells are preferably configured to allow the included anglebetween those arm members to collapse and re-expand. In such a case, theframe structure may still further include a plurality of additionalclosed-perimeter, open-centered cells that are disposed in theabove-mentioned first direction from the cells between the arm membersand that are connected to the cells between the arm members. Theadditional cells may form an annular array in which those cells areconfigured to allow the array to annularly collapse and re-expand.

In accordance with yet another possible aspect of the invention, theannulus portion of a frame structure as summarized in the paragraphprior to the preceding one may include a plurality of annularly spacedcommissure posts extending in the above-mentioned first direction. Insuch a case, the strut members may be grouped in a plurality of pairs,each pair being associated with a respective one of the commissureposts, with that commissure post being between the strut members in theassociated pair.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified, planar development of an illustrative embodimentof a prosthetic heart valve component in accordance with the invention.By “planar development” it is meant that FIG. 1 shows a component thatis actually tubular. But FIG. 1 and other similar FIGS. show thiscomponent as though cut along a vertical line and then laid out flat.

FIG. 2 is a simplified elevational view of a representative portion ofthe FIG. 1 apparatus in the operating condition of that apparatus thatis shown in FIG. 1.

FIG. 3 is a simplified elevational view of the FIG. 2 structure inanother operating condition of the apparatus.

FIG. 4 shows a portion of what is shown in FIG. 1 on a larger scale.

FIG. 5 shows another portion of what is shown in FIG. 1 on a largerscale.

FIG. 6 is similar to FIG. 1 for another illustrative embodiment inaccordance with the invention.

FIG. 7 is similar to FIG. 6 for yet another illustrative embodiment inaccordance with the invention.

FIG. 8 repeats FIG. 7 with some additional reference information addedto facilitate explanation of certain possible aspects of the invention.

FIG. 9 shows a portion of what is shown in FIG. 8 on a larger scale.

FIG. 10 is a simplified perspective or isometric view of apparatus ofthe type that is shown in FIG. 8.

FIG. 11 is similar to FIG. 10 from another angle.

FIG. 12 is similar to a portion of FIGS. 10 and 11 from still anotherangle.

FIG. 13 shows a portion of what is shown in FIG. 10 on a larger scale.

FIG. 14 is similar to FIG. 5 for another illustrative embodiment of theinvention.

FIG. 15 is similar to FIG. 14 for still another illustrative embodimentof the invention.

DETAILED DESCRIPTION

All of the FIGS. that accompany this specification show prostheticaortic valve embodiments. The lower annular part 60 of each of theseembodiments is implanted in or near the patient's native aortic valveannulus. Thus the lower annular part 60 may sometimes be referred to asthe annulus part or the annulus portion. The upper annular part 20 or220 of each of these embodiments is implanted in the patient's nativeaorta, typically downstream (in the direction of blood flow) from thepatient's native valsalva sinus. Thus the upper annular part 20 or 220may sometimes be referred to as the aortic part or the aortic portion.The struts 40 that connect the upper and lower parts of each embodimenttypically extend through the patient's native valsalva sinus.

All of the FIGS. that accompany this specification (except for FIG. 3)show the depicted valve component (i.e., frame structure 10, 100, or200) in the circumferentially (or radially, or annularly, ordiametrically) collapsed condition. It will be explained below where inthese valve components the expansion occurs when the valve re-expands.All of the FIGS. that accompany this specification omit the flexiblevalve leaflets that are nevertheless present in valves in accordancewith this invention. Examples of how such leaflets may be provided andsecured to the components (e.g., frame structure 10, 100, or 200) thatare shown in the accompanying FIGS. are shown in Braido U.S. patentapplication Ser. No. 11/906,133, filed Sep. 28, 2007, which is herebyincorporated by reference herein in its entirety. All of the FIGS. thataccompany this specification also omit other components that may be partof valves in accordance with this invention. Examples of such possibleother components are tissue layers for cushioning and/or buffering,fabric covers, and the like. (See again the above-mentioned Braidoreference.) Some of the accompanying FIGS. show the metal framecomponent (e.g., 10, 100, or 200) of the valve as though cut along alongitudinal axis and laid out flat. This is only a matter of depiction,however. In all cases the metal frame component 10, 100, or 200 isactually a complete and continuous ring or annular structure, such as isshown in some others of the accompanying FIGS.

The present invention is based on a unique collapsing and expandingframe mechanism concept, several illustrative embodiments of which areshown in the accompanying FIGS. Prosthetic valves in accordance with theinvention include such a frame 10, 100, or 200, as well as tissue orpolymer valve leaflets (not shown in the accompanying FIGS., asmentioned above). The frame 10, 100, or 200 can be laser-cut fromvarious metals, a particularly preferred metal being nitinol. Forexample, the starting nitinol metal stock may be a tube. Afterprocessing through appropriate annealing steps, the nitinol stent 10,100, or 200 takes on the final shape and dimensions intended for thefinal deployment size and shape of patient anatomy. This so-called finalshape/dimension is the expanded size of the metal frame 10, 100, or 200,not the collapsed size shown in all of the accompanying FIGS. (with theexception of FIG. 3).

The polymer or tissue valve leaflets (not shown as mentioned above) canbe attached to the frame 10, 100, or 200 by various means such assuturing, stapling, or the like. The frame and leaflets (and any otherpossible components as mentioned above) can then be collapsed inpreparation for integration into a delivery system. Various deliverysystems can be employed to deliver and deploy the valve at the intendedtarget (implant site) in the patient. The delivery system may depend tosome extent on the desired valve implantation approach. Examples ofpossible approaches are percutaneous retrograde (i.e., percutaneous,meaning catheter-like at least partly through blood vessels of thepatient's circulatory system; and retrograde, meaning opposite the bloodflow direction), percutaneous antegrade (i.e., antegrade, meaning withthe blood flow direction), transapical (i.e., through the apex of theheart), etc. Although the delivery system may thus include certainvariations depending on how the implant site is to be approached, allsuch systems may have similar valve interface mechanisms for collapsingthe valve. The valve can be deployed in the same manner for any of thepossible approaches, i.e., withdrawal of a sheath that is initiallyloaded over the collapsed valve to keep the valve in a collapsed state.As the sheath is pulled back, the portions of the stent or frame 10,100, or 200 that become uncovered by the sheath will start to deploy.The sheath can be pulled in either direction relative to the valve(i.e., either proximally or distally, where proximal means closer to ortoward the operator of the delivery apparatus, and distal means fartheror away from the operator of the delivery apparatus), but this may alsodepend on the delivery system design and the approach, as well as ondesired performance features. After the valve is fully deployed, thedelivery system can still retain the ability recapture the valve forrepositioning or retrieval/removal of the valve at the discretion of theoperator.

FIG. 1 shows an illustrative embodiment of the metal frame 10 of aprosthetic heart valve in accordance with the invention. As mentionedearlier, FIG. 1 shows frame 10 as though cut longitudinally (i.e., alonga vertical axis in FIG. 1) and laid out flat. However, frame 10 isactually a hollow annular (ring-like or tubular) structure in which theleft and right edges of what is shown in FIG. 1 are integrally connectedto one another. In other words, frame 10 actually forms a continuous,hollow annulus or annular structure (e.g., lying in an approximatelytubular geometric space).

In FIG. 1 reference 20 points to the top ring (or aortic portion) cellsof frame 10. Eyelets 30 are provided to facilitate stent retrieval withthe delivery system. Connecting struts 40 connect top ring 20 to thebottom ring of cells (or annulus portion) 60. Commissure posts 50project upwardly to some extent from bottom ring 60.

FIG. 1 shows a flat development of frame 10 in its annularly compressedor collapsed condition. (Again, such flat depictions of what areactually tube-like structures are employed solely to simplify some ofthe FIGS. herein.) This is the condition in which closed-perimeter,open-centered cells 20 and 60 are relatively compressed from left toright as viewed in FIG. 1 (see also FIG. 2). A valve may be deliveredinto a patient in this collapsed condition. FIG. 3 shows what happens tosuch a representative cell 20/60 (from FIG. 2) when frame 10 expands tothe implant and operating condition. Comparison of FIGS. 2 and 3 showsthat (in FIG. 3) each cell 20 or 60 becomes much wider in the left-rightdirection. These increased cell widths add up to make the expanded frame10 much larger in circumference than the collapsed frame (FIGS. 1 and2).

It is briefly mentioned again that when the valve is implanted in thepatient, top or aortic ring cells 20 are disposed in the patient's aorta(e.g., downstream from the valsalva sinus), connecting struts 40 passthrough the valsalva sinus, and bottom or annulus ring cells 60 aredisposed in or near the patient's native aortic valve annulus.Commissure posts 50 may be rotationally aligned with the patient'snative aortic valve commissures. The prosthetic valve includes threeflexible leaflets (not shown herein, but see again the above-mentionedBraido reference). Each of these leaflets basically extends between arespective pair of annularly adjacent ones of commissure posts 50. Leftand right edge portions of each leaflet are respectively attached to theposts 50 in the pair of posts between which that leaflet extends. Alower edge portion of each leaflet is attached to bottom ring structure60 below and between the posts 50 between which that leaflet extends.The upper edge of each leaflet is relatively free and is able to movetoward and meet the upper edges of the other two leaflets to close thevalve, or to move radially out away from those other two leaflet upperedges to open the valve. The direction of blood flow through the valve(when open) is upward as viewed in FIG. 1.

It should be noted that in FIG. 1 and in all other embodiments of thisinvention the bottom ring cell 62 immediately below each commissure post50 is different from the other bottom ring cells 60. In particular,bottom ring cells 62 are stronger and more resistant to collapse (in adirection that is circumferential of the valve (left-right as viewed inFIG. 1)) than the other bottom ring cells 60. This greater strength ofcells 62 accounts for the fact that even in the collapsed conditionshown in FIG. 1, cells 62 remain relatively open, while all of the othercells 60 are very nearly closed in the circumferential direction.Indeed, the condition of cells 62 shown in FIG. 1 may also be verynearly the fully expanded condition of those cells. Most of the annularcompression and re-expansion of bottom ring 60 may occur in cells otherthan cells 62, with cells 62 remaining at or nearly at the same size (inthe circumferential direction) in both the collapsed condition and there-expanded condition of the valve. Cells 62 can be given theabove-described greater strength, for example, by increasing the widthand/or thickness of the members that form those cells.

To quantify the possible feature of the invention that has just beendescribed, when a valve frame like 10 with this feature is subjected toan annular collapsing force that reduces annulus portion 20 to 50% ofits full (expanded) size as an operating valve, each of cells 62 stillpreferably retains at least 75% of its full operating size width (e.g.,as measured in the area indicated by the dimension W in FIG. 5). Notethat each substructure that includes a commissure post 50 and a cell 62may be described as a Y-shaped structure (with post 50 forming the basemember of the Y, and with cell sides 63 a and 63 b forming the divergingarm members of the Y). The cell 62 of this Y-shaped structure is closedby a linking member 63 c that interconnects the arm members 63 a and 63b remote from where the arms begin to diverge from one another. Theupper end of post 50 is a free end portion. The included angle A betweendiverging arm members 63 a and 63 b is preferably less than 90°.Dimension W is typical of how the open space between arms 63 a and 63 bcan be measured. Linking member 63 c may help to resist collapse of thisopen space; but, on the other hand, it may still allow some change inthe size of the cell 62 for which it provides some of the perimeterstructure.

The following summarizes some of the benefits and other features of theabove-described approach. The increase in stiffness of commissure posts50 and associated cells 62 can help to maintain repeat cycle deflectionover time. (Such repeat cycle deflection may include deflection of posts50 in the radial direction in response to each cycle of opening andclosing of the valve after it has been implanted and is functioning in apatient.) Making parts 50/62 relatively non-collapsible andnon-expanding facilitates configuring the geometry of those partswithout major constraints in order to achieve a desiredflexibility/stiffness balance (e.g., in the radial direction). Note thatconnecting struts 40 are directly attached to the flexing posts 50/62 toprovide additional support and/or stiffness. The following furtherexplains the mechanism of stent post flexibility/stiffness. Thisperformance can be controlled by varying the contact point of theconnecting arms 40 along the inverted Y post arms. For example,connecting struts 40 may be connected (1) at or near the tip of theposts 50 in one extreme possibility, (2) at or near the bottom of theinverted Y structure in the other extreme possibility, (3) or anywherein between these two extremes. This can greatly increase or decrease theability of the post tip to deflect inwardly. This is another way thatthe flexibility/stiffness can be controlled (in addition to changing thewidth and/or thickness of the inverted Y arms).

Another possibly advantageous feature that is illustrated by FIG. 1 isthe absence of frame geometry and metal below each post 50 and cell 62.In other words, bottom ring 60 does not extend down below posts 50nearly as far as it extends down elsewhere. The resulting recesses 64(extending upwardly into the structure) help the implanted valve avoidinterfering with the patient's adjacent mitral valve.

Each commissure post 50 has several eyelets 52 for easier leafletintegration (attachment).

Eyelets 30 in top ring cells 20 can be used to pass a wire (e.g., ofnitinol) or other tether through frame 10 and then through a centrallumen of the delivery system. This aids in reducing the expanded top(aortic) ring diameter for retrieval of the valve for purposes ofrepositioning or removing the valve. In other words, the above-mentionedtether(s) through eyelets 30 can be tensioned to pull eyelets 30 andadjacent frame elements radially inwardly so that they will again fitinto a delivery system sheath. For example, the above-described tetherand eyelet 30 structure can also help to prevent the stent 10 fromcatching on an edge of a sheath that is part of the delivery apparatusas mentioned above. Once the frame 10 is thus back in the deliverysystem, that system can be used to reposition and redeploy the valve, oralternatively to completely remove the valve from the patient.

As has been noted, FIG. 4 shows an enlargement of the upper portion offrame 10 from FIG. 1. FIG. 5 shows an enlargement of the lower portionof frame 10 from FIG. 1.

FIG. 6 is a view similar to FIG. 1 showing an alternative frameembodiment 100. The only difference between frame 10 and frame 100 isthat in frame 100 cells 62 are diamond-shaped and extend down to orclose to the plane containing the bottoms of other bottom (annulusportion) ring cells 60. (The same reference numbers are used in FIGS. 1and 6 for elements that are the same or similar.) This means that frame100 does not include the upwardly extending recesses 64 that are shownin earlier FIGS. and described above for frame 10.

FIG. 7 shows an illustrative embodiment of possible further features inaccordance with the invention. Again, these features can help tofacilitate easy repositioning and/or retrieval of the valve. FIG. 7 isanother view similar to FIGS. 1 and 6, but FIG. 7 shows a modified frameembodiment 200. Elements in FIG. 7 that are the same as or similar toelements in earlier FIGS. have the same reference numbers again in FIG.7. In particular, the differences from frame 10 are in top ring area(aortic portion) 220.

As shown in FIG. 7, the top ring 220 cell design is such that there areno elbow struts that can catch on a sheath of delivery apparatus duringvalve collapsing. This is achieved by connecting all expandable cells intop ring 220 down to the six connecting struts 40 in a tapered manner.More specifically, the lower-most points or elbows 223 a (FIG. 9) of thetop-most row of cells 222 also form the side mid-point nodes of cells224 in a next-lower row of the top ring. The lower-most points or elbows225 a of cells 224 form the side mid-point nodes of cells 226 in a stilllower row of the top ring. The lower-most points or elbows 227 a ofcells 226 blend into (i.e., are the attachment points for) struts 40. Asa consequence of this, no cell 222, 224, or 226 in top ring 220 has adownwardly projecting elbow that is exposed (i.e., does not smoothlyblend into some further, lower structure, ultimately leading smoothlyinto struts 40). There are thus no exposed, downwardly pointing elbowson any top ring cells that could catch on a sheath that is moving (frombelow as indicated by arrow 203 in FIG. 8) back up over the top ringstructure in order to re-collapse that structure for repositioning orretrieval of the valve.

Another way to describe the feature illustrated by FIGS. 7-9 is to startfrom struts 40 and work upward. The upper end 227 a of each strut 40 isthe starting point for two arms (e.g., 228 a and 228 b) that divergefrom one another as one proceeds upwardly from that starting point. Theincluded angle B between these two arms is preferably less than 90°.Each of these arms 228 a/b continues upwardly until it meets and joinsthe circumferentially (or annularly) adjacent arm 228 a/b extendingupwardly from another circumferentially (or annularly) adjacent one ofthe starting points 227 a. There is no structure between any of thecircumferentially adjacent arms 228 that emanate from circumferentiallyadjacent ones of starting points 227 a. Thus there is no such structurethat can catch on delivery apparatus that is moving upwardly (arrow 203in FIG. 8) to re-collapse and re-enclose the upper portion of frame 200.All of the structure of aortic ring 220 is either between the pairs ofarms 228 a/b that emanate from the same starting point 227 a or upwardlybeyond that structure. Struts 40 and arms 228 a/b can thus act tosmoothly feed all of aortic ring 220 back into delivery apparatus thatis moving upwardly as indicated by arrow 203 in FIG. 8.

The same principle illustrated by FIGS. 7-9 can be alternatively oradditionally applied to bottom ring structure (annulus portion) 60 forthe reverse deployment option (i.e., deployment of annulus portion 60first). In other words, bottom ring cells 60 (other than 62 and posts50) can be blended into connecting struts 40 via one or more interveningrows of additional bottom ring cells to avoid exposed, upwardly facingelbows (other than posts 50).

The point mentioned in the immediately preceding paragraph isillustrated by FIGS. 14 and 15 (which show two different illustrativeembodiments). In FIG. 14 annulus portion 360 includes three rows ortiers of closed-perimeter, open-center cells 362, 364, and 366. All ofthe cells 362 in the topmost row begin (at their upper ends) at points367 a that are at the bottom ends of struts 40. The rows of cells 364and 366 below top row 362 fan out gradually from the topmost row, sothat no cell in any row has an upwardly pointing corner that is not alsopart of the side structure of another cell that is higher up. In otherwords, from each starting point 367 a, two arms 368 a and 368 bgradually diverge and continue relatively smoothly down as far as isnecessary to include the upper elbows of all cells 362, 364, and 366that are between those arms. All cells in annular portion 360 arebetween some such pair of diverging arms 368 a and 368 b. (Again, theincluded angle B between each such pair of arms 368 a and 368 b is lessthan 90°.) Avoidance of exposed, upward-pointing cell corners in thisway facilitates reintroduction of annulus portion 360 into a downwardlymoving delivery apparatus sheath in the event that the prosthetic valvemust be repositioned in the patient or withdrawn from the patient. Theonly upwardly pointing structures that are not thus prevented from beingexposed are commissure posts 50. However, these posts 50 can be designedto have a slight inward tilt toward the central axis, which can helpprevent a frame-collapsing sheath from catching on these posts as thesheath passes over them.

Again it is emphasized that the principles illustrated by FIGS. 7-12(i.e., no exposed cell corners in aortic portion pointing toward annulusportion) and FIGS. 14 and 15 (i.e., no exposed cell corners in annulusportion pointing toward aortic portion) can be combined in one valveframe in accordance with this invention.

FIG. 15 shows an alternate embodiment of what is shown in FIG. 14.Reference numbers in FIG. 15 in the 400 series that are otherwisesimilar to reference numbers in FIG. 14 in the 300 series refer tosimilar elements. The description of FIG. 15 can therefore be somewhatabbreviated because the description of FIG. 14 applies again to FIG. 15with only the above reference number difference. The major differencebetween FIGS. 14 and 15 is in where the cellular structure of theannulus portion connects to the structure of commissure post cells50/62. In FIG. 14 the upper-most of these connection points 369 a/b arerelatively close to the bottom of cells 62. In FIG. 15, on the otherhand, the upper-most of these connection points 469 a/b are closer tothe tops of cells 62. As is pointed and described elsewhere in thisspecification, this kind of variation can be used to affect thestiffness of the commissure posts structures 50/62. For example, allother things being equal, the commissure post structures 50/62 in FIG.14 tend to be more flexible (e.g., for deflection radial of theprosthetic valve) than the commissure post structures 50/62 in FIG. 15.The length of cantilevering of the structure 50/62 is greater in FIG. 14than in FIG. 15.

FIGS. 10 and 11 show frame 200 in the round, but still in the collapsedcondition. FIG. 12 shows an enlargement of the upper portion of what isshown in FIGS. 10 and 11. FIG. 13 shows an enlargement of the lowerportion of what is shown in FIGS. 10 and 11.

The following paragraphs highlight various aspects of the invention.

Flexible stent frame posts 50 separated from the main frame structure onthe upper or blood outflow end, but attached to the stent structure atthe lower or blood inflow end of the posts. This allows the stent(especially posts 50) to flex and deflect to accommodate valve tissuefunction in the open/closed cycles.

At least three non-expanding stent post members 50/62. This allows forbalancing the stiffness of the bending/flexing post 50/62 by dialing ingeometry of the post as well as the width of its struts (i.e., the sidemembers of cells 62).

At least three connecting members 40 that connect the stent's top(outflow) expanding ring geometry 20/220 with the stent's bottom(inflow) expanding ring geometry 60.

The connecting struts 40 can be attached to the stent's posts 50/62 atvarious locations to provide additional means of adjusting stiffness, aswell as controlling stent post 50/62 flexibility and deflection.

Connecting struts 40 can also be attached to any of the bottom cells.More than six connecting struts 40 are also possible if it is desired toconnect every cell at the top ring with every cell at the bottom ring.The geometries of the connections between top and bottom rings can varysignificantly, but the objective is to eliminate exposed elbows that canpotentially cause catching when re-sheathing.

A unique and differentiated top ring geometry 220 design that includesseveral struts (cell perimeter members) and closed and open cells thatare disposed in rows 222, 224, and 226. As the rows approach theconnecting struts 40, the number of cells and struts (cell perimetermembers) decreases in a manner that forms a smooth and streamedtransition from the very top (outflow end) down to the point of makingconnection with the six struts 40. The geometry is such that there areno exposed strut (cell perimeter member) elbows that are not connectedto the remainder of the geometry such that they can catch and hang onthe edge of an advancing sheath during re-sheathing for repositioning orfor retrieval.

The same geometry described in the above paragraph can be applied to thestent's bottom ring 60 (e.g., as shown in FIGS. 14 and 15).

This stent invention can incorporate the above-described geometry on thetop ring only, the bottom ring only, or on both rings. Withincorporation on the top ring only, the sheath can only be advanced fromthe blood inflow to the blood outflow end of the stent when recapture isdesired. Similarly, if the geometry is incorporated on the bottom ringonly, the sheath can only be advanced from the blood outflow to theblood inflow end of the stent. Finally, if the geometry is incorporatedon both rings, the sheath can be advanced from either direction whenstent collapsing for recapture is desired.

The geometry design described above can vary in strut (e.g., cellperimeter member) width, thickness, shape, taper, and/or length tocreate a desired balance for that geometry that will allow for reducedstrain during initial processing expansion, collapsing, andre-expansion. Therefore, the design can utilize various combinations ofthese variations to achieve the right balance.

The mid-section 40 of the stent between the top and bottom rings can bedesigned to expand to fit and self-anchor in the valve sinus area (i.e.,the valsalva sinus). Also, it can be designed with no curves (straightmembers 40) and serve the purpose of connecting the stent's top andbottom rings. Finally, it can be designed to have predetermined bendsthat may have some functional aspects when collapsed for delivery, aswell as in the deployed functional state.

The stent geometry incorporates several eyelet designs (e.g., 30) thatare disposed at various locations of the stent. Depending on theirlocations, these eyelets serve different functions. When disposed aroundthe top ring 20/220, they can facilitate stent collapsing for certainstent geometry designs by threading a temporary thin nitinol wire sutureor other appropriate tether member to loop through the eyelet(s) 30 andback into the central lumen of delivery apparatus. When the stent ispartially deployed and recapture is desired, the wires can be pulledproximally, which causes the geometry to taper and “funnel” radiallyinwardly into the delivery system sheath (tube).

The stent posts 50 can incorporate eyelets 52 to facilitate leafletintegration and attachment to the posts with appropriate means (e.g.,with sutures).

The stent's bottom (inflow) ring 60 geometry may also incorporateeyelets 66 at various locations that can be utilized for leafletintegration, cuff integration, or for attaching members that can assistin re-collapsing the valve during repositioning and retrieval.

The eyelets or other similar apertures can be disposed at differentlocations and in various combinations for purposes such asstent/tissue/cuff integration and/or stentdeployment/recapture/repositioning. Therefore, eyelets can be located atthe corners of cells, or between cells at the top and bottom rings, oranywhere in between.

The stent geometry at both the inflow and outflow edges can incorporateadditional anchoring features so the stent remains secured during thecardiac cycle.

The stent frame has sections designed to allow clearance of the coronaryarteries, thus not obstructing critical blood flow to the heart. Thisaspect of the invention is illustrated by reference numbers 240 in FIGS.such as FIGS. 7-15. When the valve frame opens up (expands annularly) atthe implant site in the patient, these areas 240 between struts 40 willbecome relatively large, open, and unobstructed areas. If posts 50 arealigned with the patient's native valve commissure posts, open areas 240(which are circumferentially offset from posts 50) will tend to bealigned with the patient's native coronary artery ostia. This helps toensure that no part of the prosthetic valve blocks blood flow from theaorta into the coronary arteries. This property of the prosthetic valveis enhanced by the use of a design (e.g., like that shown in FIG. 7) inwhich one or both ends (upstream and/or downstream) of areas 240 arefree of exposed cell elbows as described elsewhere in thisspecification. For example, there are no exposed, upstream-pointing cellelbows or corners between the arms that are labelled 228 a and 228 b inFIG. 11. This helps to keep the area that is labelled 240 in FIG. 11open for avoidance of obstruction of a patient's coronary artery ostia.

The stent can incorporate a collapsible cuff to promote tissuein-growth, thus preventing perivalvular leaks.

The cell elbow geometry can incorporate unique geometry thatstress-relieves the stent, as well as allowing for larger cell expansionand providing locations that can be used for leaflet and cuffintegration.

The stent geometry design can have features (e.g., recesses 64) torelieve impingement on the mitral valve when expanded within calcifiedleaflets.

It will be understood that the foregoing is only illustrative of theprinciples of the invention, and that various modifications can be madeby those skilled in the art without departing from the scope and spiritof the invention. For example, the number of closed-perimeter,open-centered cells (e.g., 20 or 60) that is used to form each ring ofsuch cells can be more or less than the numbers shown in theaccompanying FIGS. Similarly, the number of rows or tiers of such cells(e.g., 20 or 60) that are used in the aortic or annulus portions offrame 10, 100, or 200 can be different from the numbers shown in theaccompanying FIGS.

The invention claimed is:
 1. A frame structure for a prosthetic heart valve comprising: a plurality of Y-shaped structures disposed in an annular array in which the Y-shaped structures are spaced from one another in a direction that is annular of the array, each of the Y-shaped structures including a base member having a first free end portion and an opposite second end to which a first end of each of two arms of the Y-shaped structure is connected, the arms of each of the Y-shaped structures diverging from one another in a direction away from the second end to define a space between the arms, the space extending in the annular direction; and a plurality of connecting structures, each connecting structure extending between a respective pair of annularly adjacent ones of the Y-shaped structures, each connecting structure interconnecting the Y-shaped structures in the associated pair, each connecting structure being collapsible and re-expandable in the annular direction, each of the Y-shaped structures being sufficiently strong to maintain at least 75% of the space between its arms when the array is subjected to an annular collapsing force that collapses the array to 50% of an initial annular size, wherein the arms of the Y-shaped structures are not shared by any of the connecting structures.
 2. The frame structure defined in claim 1 wherein each of the connecting structures is connected to the arms of the Y-shaped structures in the associated pair but not to the base members of those Y-shaped structures.
 3. The frame structure defined in claim 1 wherein each of the Y-shaped structures further includes a linking member that interconnects the arms of the Y-shaped structure at a location that is spaced from the second end.
 4. The frame structure defined in claim 1 wherein the array lies in an approximately tubular geometric space that surrounds a central longitudinal axis, and wherein the base member of each of the Y-shaped structures is approximately parallel to the longitudinal axis.
 5. The frame structure defined in claim 4 wherein all of the first free end portions point in a first direction parallel to the longitudinal axis.
 6. The frame structure defined in claim 5 wherein the first free end portions all extend farther in the first direction than any portions of any of the connecting structures.
 7. The frame structure defined in claim 6 wherein no portions of any of the Y-shaped structures extend as far opposite the first direction as portions of the connecting structures.
 8. The frame structure defined in claim 7 wherein each of the Y-shaped structures further includes a linking member that interconnects the arms of the Y-shaped structure at a location that is spaced from the second end.
 9. The frame structure defined in claim 6 wherein each of the Y-shaped structures further includes a linking member that interconnects the arms of that Y-shaped structure at a location that is spaced from the second end.
 10. The frame structure defined in claim 9 wherein the linking member of each of the Y-shaped structures extends approximately as far opposite the first direction as portions of the connecting structures.
 11. The frame structure defined in claim 5 further comprising: an aortic portion that is spaced from the Y-shaped structures and the connecting structures in the first direction, the aortic portion being annular about the longitudinal axis and being annularly collapsible and re-expandable; and a plurality of strut members for attaching the aortic portion to the Y-shaped and connecting structures of the frame structure.
 12. The frame structure defined in claim 11 wherein the aortic portion comprises: a plurality of open-centered, closed-perimeter cells disposed in an annular array in which connection points between annularly adjacent cells are at intermediate points along sides of the cells and each cell includes first and second ends that respectively point in the first direction and opposite the first direction.
 13. The frame structure defined in claim 12 wherein the second end of each of the cells includes an eyelet for attaching a tether member that can be used to pull the eyelet radially in toward the central longitudinal axis. 